I am a new user, moving from Windows 7.
I attempted to install Qubes OS, which, despite my system lacking VT-d, succeeded. As expected, according to UserFaq.
There are only USB devices available. On the initial setup (Installation guide — Qubes OS Documentation), both checkboxes for Automatically accept mice and Automatically accept keyboard were checked.
It was expected that, after the 1st boot (which is successful), all subsequent boot attempts would succeed. Unfortunately, that is not what happens. All boot attempts halt at the login screen, where mouse and keyboard have no effect. The only way to have both mouse and keyboard working at login (and from then on), is to reboot, edit grub, and add qubes.skip_autostart.
The seemingly “temporary” solution qubes.skip_autostart seems to be the only effective solution. No other attempts succeeded (Installation troubleshooting — Qubes OS Documentation, USB qubes — Qubes OS Documentation). It was not attempted to install Qubes OS without sys-usb.